What is flehmen behavior in artiodactyl courtship?

In artiodactyls, flehmen is a specialized courtship behavior used by males to assess the reproductive status of females. During this process, the male typically sniffs or licks the female’s urine and then raises his head slightly while curling his upper lip.12

This action facilitates the exposure of the vomeronasal organ—also known as Jacobson’s organ—to scents or pheromones. By curling the lips and often closing the nostrils, the animal allows chemical stimulants to reach this sensory structure, which is located on the roof of the mouth or in the nasal cavity. In many artiodactyls, this is made possible by a groove on the hard palate that connects the oral cavity to the vomeronasal organ.342

This behavior is a critical component of reproductive signaling, enabling the male to recognize when a female is in estrus.12